A pergola is a type of structure originally employed in gardens and similar environments to support, for example, woody vines, or to provide a horizontal open-work roof-like structure over outdoor areas, such as patios, terraces and walkways. Pergola structures continue to be used to shelter patios, terraces and walkways and for landscaping purposes, as decorative structures or for screening unwanted view, and are often for utilitarian purposes, such as sheltering storage areas and parking areas for vehicles.
A classic pergola type structure includes a plurality of upright posts typically arranged around the periphery of a rectangular area and covered by a roof formed of a rectangular grid or lattice comprised of a first layer of carrying rails or beams supported by the upright posts and an upper layer of cross rails or beams supported by and orthogonal to the carrying rails. A pergola structure may, however, assume plans other than the rectangular or square form, such as two or more mating rectangles or squares or a multi-angular plan, with appropriate adaptations in the details of the post and rail assemblies. In addition, one or more sides or ends of a pergola structure may be comprised of another structure, such as the side of a house or a wall.
Both classical and contemporary pergola structures, however, present a number of problems. For example, although pergola structures are comprised of a limited number of types or different forms of elements, that is, upright posts, carrying rails and cross rails with a few decorative trim elements, a given pergola structure is comprised of a relatively large number of such elements, resulting in a complex and time consuming assembly that typically must be constructed by an experienced worker in order to obtain a relatively strong structure.
In addition, the inherent design of pergola structures is such that the elements are not mated or assembled to one another in a manner to result in an inherently strong structure. That is, and for example, the upright posts are rarely provided with any form of bracing, except by the carrying rails at their top, the cross rails are only weakly secured to the carrying rails and contribute little to the to the strength of the structure, and a pergola structure contains many joints, all of which are exposed to the weather and stress and thereby comprise points of weakness. These problems are compounded by the materials used to construct pergolas, which are classically constructed of wood, which is highly susceptible to weather and rot, particularly at the joints.
Contemporary pergola structures, including those intended for construction by relatively unskilled persons, have attempted to address at least some of these problems. For example, contemporary pergola structures typically employ man made materials, such as metal, fiberglass or various forms of plastic elements, often as shells encasing metal, fiberglass or polyvinyl chloride (PVC) structural elements assembled by, for example, nuts and bolts, screws or glues, and often in kit form for assembly by home handicraftsmen. Such structures, however, while avoiding or alleviating at least certain of the effects of weather and exposure to the elements, typically have many of the problems presented by traditional materials and constructions methods, that is, assembly of painted wood parts. That is, it is often difficult for relatively unskilled workers to assemble a satisfactory structure, and the materials used, in composition, dimensions and design, and the design of the structural elements and their assembly, often do not result in a satisfactory structure, even when assembled correctly, with the jointing of the component parts remaining a particular problem.
The present invention provides a solution to these and related problems of the prior art.